Elevation Partners, the Silicon Valley private equity firm that counts U2's Bono among its investors, announced Wednesday that it has committed up to $100 million in funding for reviews site Yelp.

It's initially investing $25 million in the Series E round, and plans to increase the investment to up to $100 million through the purchase of stock from employees whose stock has vested, as well as other eligible shareholders. Elevation co-founder Marc Bodnick will join Yelp's board of directors.

"We have been able to grow and scale our business quickly, even in the tough economic environment of the last year--a clear indicator that we've only begun to realize the potential of local search," Yelp CEO and co-founder Jeremy Stoppelman said in a release. "This investment in Yelp provides us with even more capital to focus on scaling our already proven business model and we are thrilled to have Elevation as a new partner."

Translation: They think they can get much bigger than $500 million.

And Yelp is indeed growing fast. The company said it pulled in 26 million unique visitors in the month of December, and that the number of reviews on the site doubled last year. It's not quite as clear how much money it's making. The company makes the bulk of its money from advertising--sometimes controversially--and while it certainly has a wealth of local content, Yelp hasn't yet said anything vis-a-vis profitability.

A source close to the company, however, says that Yelp first achieved a cash-flow-positive status late last year.

About the author

Caroline McCarthy, a CNET News staff writer, is a downtown Manhattanite happily addicted to social-media tools and restaurant blogs. Her pre-CNET resume includes interning at an IT security firm and brewing cappuccinos.
See full bio